To reach Orkney in Neolithic times meant building vessels strong enough to cross the Pentland Firth and safely carry cattle and timber as well as people. This requires ship design and boat-building on a substantial scale – but how? Biophysicist Dr Mark Cooper of the University of Washington has looked at ancient seacraft designs in many places, from Arctic skin boats to Pacific island outriggers, and he shows the range of possible technologies, from leather pontoons to megalithic stones serving as the keel or skeg of a trimaran to increase stability, speed and cargo capacity. He examines the evolution of Neolithic seafaring, and possible clues from the art and architecture of megalithic monuments of Northwest Europe.